The break in the manhunt for the Boston bombers came when a man whose Mercedes SUV was carjacked by the two suspects bolted from the vehicle and managed to narrowly escape.

After getting away, the carjacked man alerted police that he had been held by the marathon bombers, and police then zeroed on his cell phone -- left behind in the car -- to track the suspects.

The man, whose identity is being withheld, almost did not escape.

He was driven around by the carjackers who police say were Tamerlan and Dzhokhar Tsarnaev, robbed of $45 in his pocket, and then forced to give up his bank card and pin number which allowed the brothers to take $800 out of his bank account, according to police and the man's interview with ABC News affiliate WMUR.

When they stopped for gas, Dzhokhar Tsarnaev went inside the Shell station to buy snacks while Tamerlan Tsarnaev pumped gas, police said.

"I thought it was a very good chance for me to run," the man said. "So, I made a judgment. I used my left hand to unbuckle my belt, my right hand to open the door. I jumped out of the car and ran away across the street."

He said he could hear the older brother cursing as he was chased and the brother tried to grab him, but the victim sprinted for his life.

"He tried to catch me, but I ran very fast," the man said. "It was very scary at that moment. For me, I'm so lucky."

The victim ran across the street to a Mobile station and pleaded with cashier Tarek Ahmed for help. Ahmed told ABC News this morning that he called police and handed the phone to the carjack victim.

"I thought for a second the suspects would come in after him, and I was going to die," Ahmed said. "I thought if I could do something after the bombings, if I protect him."

The man's ordeal began when he pulled his car over to the side of the road around 11 p.m. Thursday and a man approached holding a gun to the passenger side window.

"The man asked if I knew about the Boston bomb explosion," the victim said. "He said, "I did that,'" according to WMUR. Then the suspect allegedly pulled the magazine out of his gun and showed the man a bullet and said, "I'm serious," according to the victim.

The suspect forced the victim to drive to a second location where they picked up another man, who put something in the trunk. Officials believe that was ammunition and explosives later used in a violent shooting between the Tsarnaev brothers and police on the streets of Watertown.

"They asked me where I'm from. I told them I'm Chinese," the man said. "I was very scared. I asked them if they were going to hurt me. They said they won't hurt me. I was thinking, 'I think they will kill me later.'"

The captive then made his bold move, possibly saving his own life as well as others.